Ultraviolet‐induced red fluorescence in androgenetic alopecia—indicating alterations in microbial composition

Abstract Background Ultraviolet (UV)‐induced fluorescence technology is widely used in dermatology to identify microbial infections. Our clinical observations under an ultraviolet‐induced fluorescent dermatoscope (UVFD) showed red fluorescence on the scalps of androgenetic alopecia (AGA) patients. In this study, based on the hypothesis that microbes are induced to emit red fluorescence under UV light, we aimed to explore the microbial disparities between the AGA fluorescent area (AF group) and AGA non‐fluorescent area (ANF group). Methods Scalp swab samples were collected from 36 AGA patients, including both fluorescent and non‐fluorescent areas. The bacterial communities on the scalp were analyzed by 16S rRNA gene sequencing and bioinformatics analysis, as well as through microbial culture methods. Results Significant variations were observed in microbial evenness, abundance composition, and functional predictions between fluorescent and non‐fluorescent areas. Sequencing results highlighted significant differences in Cutibacterium abundance between these areas (34.06% and 21.36%, respectively; p < 0.05). Furthermore, cultured red fluorescent colonies primarily consisted of Cutibacterium spp., Cutibacterium acnes , Staphylococcus epidermidis , and Micrococcus spp . Conclusions This is the first study to investigate scalp red fluorescence, highlighting microbial composition variability across different scalp regions. These findings may provide novel insights into the microbiological mechanisms of AGA.